I am a DL. I consider it a hobby somewhat. I live in a large metro area with lots of resale shops and pharmacies, so every so often I make my rounds to see what I can find, some days there are quite a few finds others there are none. It really "depends". I have found a lot of unique diapers this way and you get to try some out. I also fond the occasional vintage ones which sometimes go on ebay.
I also encountered a disabled girl working at one of the stores I frequent who has admitted on two occasions to wearing Pampers size 7 (once in person, I was looking for diapers, and once on the phone, again calling about diaper brands), she is 22...looks to me to be too big for them, but she says they fit her at 115 lbs. I want to get more info out of here but don't want to be creepy/nosy so I am cautious. The big thing I want to know is why an adult who would fit into adult ones would choose the children ones (with Sesame Street on them) over adult ones which wouldn't fit tight, the 7's have to be tight on her.